On the steganographic image based approach to PDF files protection
В. Н. Горбачев, Denisov, L. A., Elena Kaynarova, I. K. Metelev · arXiv (Cornell University) · 2017
Digital images can be copied without authorization and have to be protected. Two schemes for watermarking images in PDF document were considered. Both schemes include a converter to extract images from PDF pages and return the protected images back. Frequency and spatial domain embedding were used for hiding a message presented by a binary pattern. We considered visible and invisible watermarking and found that spatial domain LSB technique can be more preferable than frequency embedding using DWT.